Ive missed an exam at uni before as well,they give you the oppurtunity to resit it anyway as a second attempt in the resit period and if your extenuating circumstances are accepted then it will count as attempt number 1 and not be capped,worst case scenario they dont accept your extenuating and you have attempt number two in the resit period which is like 4-5 weeks after the first set of exams. Also for future reference whenever you ask for advice do it via email so its documented.